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A source for Robert Fludd's sevenfold rose
by Adam McLean. Article in The Hermetic Journal 1991.

The rose symbol from the titlepage of Robert Fludd's Summum Bonum, published at Frankfurt in 1629, has become well known as a Rosicrucian symbol. It has a sevenfold symmetry, seven layers of petals and its stem is formed in the shape of a cross. However, it appears that this design was not entirely an original conception for Fludd's book, as the engraver, Matthieu Merian, had used a similar grouping of symbols fourteen years earlier in an emblem book which he illustrated.

This is emblem 21 from Iacobi â Bruck Angermundt Cogn. Si. Emblemata Moralia & Bellica, Argentorati Per Iacobum ab Heyden Iconographum Anno MDCXV. M. Merian Incidebat. What is original in the reworking for Fludd's book is the cross shaped form of the rose stem and the sevenfold symmetry of the rose. This shows very clearly that Merian and the publishers of Fludd's book, while drawing on symbolism from the emblem tradition, nevertheless intended to give this symbol definite and unambiguous Rosicrucian associations.